This invention relates to sheathing materials used on the exterior surfaces of buildings, and particularly to exterior thermoplastic siding and procedures for making such siding more rigid.
For decades, the exterior of many residential and commercial buildings has been protected by xe2x80x9cfinishingxe2x80x9d or xe2x80x9csheathingxe2x80x9d materials including wood, metal, and polymer resins. Metal sheathing, such as aluminum siding, was at one point very popular, since it was more insect- and weather-resistant than wood siding, and could be anodized, painted, or laminated to provide a plurality of colors and styles. Metal sheathing also proved to be long lasting and energy efficient, but because it could not be easily sawed, clipped, or drilled with hand tools, it was relatively labor intensive to install. Additionally, metal sheathing materials had to be extremely thin to be cost efficient, and, because of their inherent lack of ductility, were susceptible to dents by minor impact loads.
In more recent times, xe2x80x9cvinyl sidingxe2x80x9d, (which is actually a resinous composition containing polyvinyl chloride), has provided a cheaper and more impact-resistant material for exterior siding panels. This material can also be provided in a wide variety of colors and patterns, but is more flexible and forgiving, and hence, will not deform plastically under minor impact loads. Thermoplastics, like polyvinyl chloride, are also easy to machine and cut and can be worked with almost any hand tool at the construction site.
It has been found, however, that vinyl siding has not always been satisfactory as an exterior sheathing material for irregular exterior wall surfaces. Due to earlier poor construction techniques, material inconsistency, or foundation settling, exterior walls in both new and old constructions are not always flat. Since vinyl siding, as opposed to metal siding, is very flexible, it usually conforms to the irregularities of the wall surface, resulting in a crooked, bowed, or unpleasing finish.
In order to compensate for this deficiency in vinyl siding, installers frequently must resort to using wooden shims which must be separately nailed to the support surface before the siding can be installed. Attempts have also been made to loosely nail the siding to the support surface so that the siding will xe2x80x9cfloatxe2x80x9d over the uneven portions of the exterior wall. In order to float the siding over the irregularities, but still provide a relatively straight and orderly appearance, the panel must be fairly rigid so as to span high and low points along the wall. Unfortunately, polyvinyl chloride, even in its most rigid state, only has a flexural modulus of about 0.5xc3x97106 psi, and a tensile strength of about {fraction (1/7)} of that of wrought aluminum.
Accordingly, there is a need for a thermoplastic-based siding panel that is more resistant to bending, or conforming to irregularities in exterior wall surfaces, but which retains its low cost and ability to be worked with ordinary hand tools at the construction site.
This invention provides exterior finishing panels having an aesthetically pleasing outwardly-facing surface. The panels include a rigid support member disposed along a portion of their length. This support member includes a flexural modulus, a measure of the materials xe2x80x9cstiffnessxe2x80x9d, which is greater than the flexural modulus of the thermoplastic sheet.
Accordingly, this invention provides vinyl siding which is stiffer and more resistant to bending along cracked, pitted, or bowed exterior wall surfaces than standard vinyl siding. The siding panels of this invention are reinforced, much like reinforced concrete is supported against tensile loads by steel rebar, to obtain a better xe2x80x9cfloatingxe2x80x9d effect along irregular surfaces. The panels are easier to handle, since they are not as susceptible to bending, and they are easier to install, since a rigid straight panel will lock into another rigid straight panel with less effort on a more consistent and predictable basis.
The exterior siding of this invention is able to ride uneven walls straighter, and presents a finished appearance which is flatter looking. The rigid panels will also provide the homeowner with a stronger and more rigid feel when the owner presses up against these newly-installed panels. Since the panels are stiffer, they can be provided in longer lengths over the current 12 foot standard length, with little chance of kinking. Since the preferred support members of this invention are also engineering thermoplastics themselves, they can be sawed with conventional hand tools, which will avoid unnecessary additional labor costs. As an additional benefit, the reinforced exterior siding panels of this invention are resistant to wind damage and xe2x80x9cblow offsxe2x80x9d, since the rigid supports will tend to distribute the wind load more efficiently to all of the nail heads.
In more preferred embodiments of this invention, siding panels are provided which include a plurality of elongated, simulated board members formed in an extruded sheet containing a rigid polyvinyl chloride. The panels of this embodiment include hook-and-groove fastening means for permitting the siding panel to be joined in overlapping fashion to an adjoining panel. These panels also include a preferred rigid support member including a flexural modulus which is relatively greater than the flexural modulus of the rigid polyvinyl chloride of the extruded sheet. The support member contains a polymer-matrix-composite which can be sawed with a standard saw blade made of steel.
The rigid support members of this invention can be fabricated from a multitude of materials including metal, thermoplastic, or thermosetting polymers and can be adhered to an inwardly-facing surface of the panel, extruded within the thickness of the thermoplastic sheet of the panel, or otherwise applied to the panel to reinforce it during handling, installation and use.